Embodiments of the inventive concept relate generally to electronic memory technologies. More particularly, embodiments of the inventive concept relate to techniques for improving the read performance of certain electronic memory technologies.
A hard disk drive (HDD) stores data in the form of magnetic patterns on a surface of a magnetic disk. The HDD reads the data by detecting the magnetic patterns using a transducer, and converting the detected patterns into a digital signal (e.g., a binary data sequence) through a series of processes, such as amplification, analog-to-digital conversion, and error correction. The HDD then transmits the digital signal to a host.
The detected patterns generally contain noise, so HDDs rely on signal processing techniques to identify the digital signal from the patterns. For instance, some HDDs use iterative decoding schemes in which a plurality of loops are performed to determine a digital signal having a relatively high likelihood given the detected patterns. In some schemes, each loop generates a putative digital signal using various decoding and/or evaluation techniques such as Viterbi decoding, parity checking, and so on. The decoding scheme then determines a bit error rate of the putative digital signal, and outputs the putative digital signal if the bit error rate falls below a predetermined threshold.
The bit error rate of the putative digital signal tends to decrease as further loops are performed; however, performing further loops also increases the amount of time required to perform a read operation. Accordingly, in an HDD employing an iterative decoding scheme for read operations, there is a tradeoff between the accuracy and the speed of the read operations.